PROJECT SUMMARY The United States is experiencing an opioid use and overdose crisis. To address the epidemic, a wide range of strategies to treat opioid use disorders are being implemented across the country, and New Jersey is expanding and enhancing medication assisted treatment (MAT) services with a State Targeted Response to the Opioid Crisis Grant. MAT is the most effective intervention for an opioid use disorder (OUD), and methadone maintenance treatment (MMT) is the most commonly prescribed MAT; however, approximately half of people who begin MMT discontinue within a year, and half of people retained in MMT have an opioid relapse within six months. Chronic pain, affecting most people on MMT, could be contributing to relapse in this group. Novel behavioral interventions that address both chronic pain and opioid relapse among people on MAT are needed. Although several behavioral therapies have shown efficacy in separately treating pain and opioid use, few interventions exist which address these co-occurring problems simultaneously. However, Mindfulness Oriented Recovery Enhancement (MORE) was recently developed to treat both pain and opioid misuse. MORE is a group intervention that combines training in mindfulness, cognitive reappraisal, and positive emotion regulation skills to target the dysfunctional cognitive, affective, and behavioral pathways that lead to opioid use relapse. Moreover, an early stage trial of MORE has demonstrated its efficacy in reducing subjective assessments of pain severity, pain related dysfunction, opioid craving, and opioid misuse. However, to date, this promising intervention has never been tested as an adjunctive therapy to prevent relapse and address chronic pain among people with an OUD on MAT. The objective of this proposal is to examine the impact of MORE on opioid relapse and chronic pain among individuals receiving MMT. Our central hypothesis is that MMT effectiveness will be enhanced by an adjunctive behavioral treatment that helps patients cope with the chronic pain, stress, and emotion dysregulation that could lead to opioid relapse. We will first conduct a small pilot study to test the feasibility of our study methods (R21; N=30). We will then conduct a larger study (R33; N=150, estimated) to assess MORE with respect to a range of clinical outcomes. Both studies will involve a 2-arm, individually randomized controlled trial design that compares MORE to MMT as usual (TAU). With the R21, we aim to pilot study protocol to determine feasibility. This study phase will focus on establishing study feasibility in recruiting, retaining, and following up study participants. With the R33, we aim to 1) determine MORE efficacy relative to TAU and 2) explore mediators of opioid use outcomes. If this study is successful, it could identify a promising intervention for helping people on MMT to cope with the stress and dysfunction associated with chronic pain, reduce their risk of opioid use relapse, and enhance their overall quality of life.